msn problemo

[alan_driver]

I am on a computer that isn't mine. It's running Win XP profeshinal 2002, and its Camp to say the least. Anyway long and short of it is it wont let me sign onto msn messenger. The username and password are correct, but it says they are not, But they ARE. It allows me to sign onto hotmail. I have tried Caps/numlock and really run out of ideas.
Help please.